Banstead, Surrey
Semi-detached rear extension in Banstead
Semi-detached rear extension in Banstead: single or two-storey extensions for semi-detached houses, with side access and one party wall. We measure the house, show you what the rules allow, price it in writing and build it.
Banstead sits in Surrey, with postcode districts including KT17, KT18 and SM7. In Banstead we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Banstead?
For Banstead we work from the South East England rate: £2,130–£3,470 per square metre of new floor, including VAT, standard specification. South East prices run above our West Midlands baseline, mainly on labour rates and clay-soil foundations.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £25,500–£41,500 |
| 4 m wide × 5 m deep (20 m²) | £42,500–£69,500 |
| 4 m wide × 6 m deep (24 m²) | £51,000–£83,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a semi-detached rear extension in Banstead?
Whether your semi-detached rear extension in Banstead needs a planning application depends on its size, your house and any local restrictions.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Banstead like to extend?
Commuter semis and detached houses make up much of Banstead, and longer gardens make England's prior approval route for deeper rear extensions worth considering. Semi-detached houses are common across Surrey, and their side access makes rear extensions quicker to build.
How a semi-detached rear extension in Banstead comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Semi-detached rear extensions near Banstead
From Banstead, the nearest places we also cover are Belmont (1.5 miles) and Sutton (1.9 miles).
- Semi-detached rear extension in Belmont
- Semi-detached rear extension in Sutton
- Semi-detached rear extension in Ewell
- Semi-detached rear extension in Cheam
- Semi-detached rear extension in Epsom
Other work in Banstead:
FAQ
Semi-detached rear extension questions in Banstead
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Do I need planning permission for a rear extension in Banstead?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Single or two-storey on a semi?
Two-storey if you need bedrooms, single-storey if you need a bigger kitchen. Planning risk is lower for single-storey.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Do you handle building control in Banstead?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Is the site visit in Banstead free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.